Gemini VI was originally scheduled to launch on October 25, 1965 and dock with the unmanned Agena Target Vehicle, but the flight was canceled after the target vehicle blew up shortly after its launch. The mission was quickly changed to a rendezvous with Gemini VII, which would carry Jim Lovell and Frank Borman on a long endurance flight. Gemini VII was launched for its 14-day mission on December 4, 1965. On December 12, the renamed Gemini VI-A launch attempt ended in a frightening engine cut-off on the pad. Thanks to the crew’s coolness, they did not eject, which would have ruined the spacecraft and endangered the astronauts’ lives. Their second launch attempt on December 15 was a success. On that date, Gemini VI-A pulled within 0.3 meters (1 foot) of Gemini VII. It was the first time in history that two vehicles had maneuvered to meet in space for a rendezvous. They flew in formation for about five hours. Then, just before Gemini VI-A was set to reenter Earth's atmosphere December 16, Tom Stafford made a radio transmission:

"We have an object, looks like a satellite going from north to south, probably in polar orbit....very low, looks like he might be going to re-enter soon....Standby one, you might just let me try to pick up that thing.”

At that point, the sound of a tiny harmonica, accompanied by small sleigh bells, could be heard playing the well-known holiday tune, “Jingle Bells.” Schirra played the harmonica, while Stafford jingled the bells. It was the first musical interlude from space. Hear the transmission. "Wally came up with the idea," Stafford told Smithsonian magazine for a 2005 article. "He could play the harmonica, and we practiced two or three times before we took off, but of course we didn't tell the guys on the ground. We never considered singing, since I couldn't carry a tune in a bushel basket."

The two astronauts had prepared for the performance by attaching dental floss and Velcro to the instruments so they could be hung on the wall of the spacecraft when not being used. Stafford and Schirra donated the instruments to the National Air and Space Museum in 1967. They are on display in the Apollo to the Moon exhibition in the Museum in Washington, DC.